A diamond semiconductor is a wide gap semiconductor having a large band gap energy of 5.5 eV. The diamond semiconductor is not only firm and has high thermal conductivity (20 W/cm·K), but also has excellent material properties, such as high carrier mobility (electron mobility of 4500 cm2/V·sec, hole mobility of 3800 cm2/v·sec) and high breakdown field intensity (10 MV/cm). Accordingly, the diamond semiconductor is a material having excellent properties as a semiconductor with ultrahigh breakdown voltage and ultrahigh efficiency.
To date, a diode, a transistor, or the like using the diamond semiconductor and having a Schottky junction has been actively developed.